The present invention relates in general to lens advancement devices, and, more particularly, to an ophthalmic dial advancement system for vision testing apparatuses, such as an ophthalmic refractor of the type which utilizes a single dial sphere control for advancing the lens power of at least one of the lenses positioned within the lens housing of the ophthalmic refractor.
Traditionally, vision testing apparatuses, and, more particularly, ophthalmic refractors, have utilized a single dial sphere control, or "diopter dial," for advancement of the lenses within the apparatus housing in 1/4 diopter steps. Accordingly, one complete rotation of the diopter dial would advance the lens through four different diopter powers--wherein one diopter power focuses on an image at a distance of one meter; a two diopter power focuses on an image at a distance of one half of a meter, etc. Such advancement of the diopter dial, and in turn, the diopter power, is necessary to determine the strength of the corrective eye lenses which a patient will need.
Actual advancement of the diopter power is effectuated by the practitioner directly advancing the diopter dial with his or her hand until he or she actually "feels" the lenses within the refractor properly advance to the next 1/4 diopter step. Such a "feel" is achieved by slight resistance imparted to the diopter dial. Unfortunately, inasmuch as diopter dials are generally engineered for smooth and easy advancement, it is not uncommon for a practitioner to inadvertently advance the diopter dial past the next intended diopter step--thus causing additional manipulation of the diopter dial, and, quite possibly, an incorrect diagnosis of the patient's vision.
Although such prior art vision testing apparatuses do offer the advantage of a single dial sphere control (diopter dial) for the advancement of the diopter power, few, if any, have provided a separate lens rotation member which not only reduces the likelihood of excessive advancement of the diopter dial during advancement of the diopter power, but which also imparts increased sensitivity to the practitioner's hands during such advancement--thereby substantially reducing inadvertent under and/or over rotation of the diopter dial with respect to the desired diopter power. Furthermore, few, if any of such prior art has provided such a cooperating lens rotation member which is alternatively positionable between a first engaged position and a second disengaged position with respect to the diopter dial, for alternative advancement of the diopter dial directly or indirectly, with or without the cooperating lens rotation member being engaged therewith respectively.
Additionally, inasmuch as prior art ophthalmic refractors have their adjustment dials and knobs positioned on or partially exposed to the surface of the lens housing which is adjacent to the practitioner during an eye examination, it is not uncommon for the patient to inadvertently, or through curiosity, place his or her hands on the testing equipment, and in turn, on one or more of the adjustment dials and knobs. Inasmuch as the diopter dial has its advancement portion positioned adjacent to the outer peripheral side surface of the lens housing, it is this critical adjustment dial which a patient's hands would most likely contact--thereby potentially moving the diopter dial and, in turn, inadvertently altering the diopter step. Although a patient's inadvertencies and/or curiosities with respect to touching the adjustment mechanisms, and, more particularly, the diopter dial, cannot be totally curtailed, few, if any prior art vision testing apparatuses teach, much less disclose, a barrier member which shields exposure of the diopter dial to a patient, while at the same time serving as a guide for utilization of the present dial advancement system, as a function of the practitioner's manipulation during the examination procedure.
It is thus an object of the present invention to provide an ophthalmic dial advancement system which provides a barrier member attached to a vision testing apparatus which helps reduce inadvertent, or curiosity, contact by a patient with the adjustment mechanisms, and more particularly, the diopter dial, on the lens housing, as well as which can serve as a hand guide for the practitioner utilizing the lens rotation member or, when directly advancing the diopter dial.
It is further an object of the present invention to provide an ophthalmic dial advancement system which includes an integrateable lens rotation member for facilitating indirect and more precise and sensitive advancement of the diopter dial, and, in turn, the diopter steps.
It is also an object of the present invention to provide an ophthalmic dial advancement system which includes a lens rotation member which is alternatively positionable between a first engaged rotational position, with respect to the diopter dial, and a second disengaged rotational position.
It is still further an object of the present invention to provide an ophthalmic dial advancement system wherein the diopter dial can be alternatively advanced directly regardless of engagement or disengagement relative to the lens rotation member.
These and other objects of the present invention will become apparent in light of the present specification and drawings.